<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Document</title>
</head>
<body>
<script>
  function c (a) {
  }
  c.prototype.b = 'a';

  var d = new c;
  d.name = 1;

  alert(c.prototype.isPrototypeOf(d))

  for (attr in d) {
    alert(d.hasOwnProperty(attr))
    if (d.hasOwnProperty(attr)) {
      console.log(attr) // name
    }
  }
</script>
</body>
</html>